VIENNA • In his opening to China more than 40 years ago, Richard Nixon made a huge Cold War gamble that he could forge a working relationship with a communist country that had built a small arsenal of nuclear weapons and had long-term ambitions for global power.
For US President Barack Obama, the deal struck yesterday with Iran represents a similar leap of faith, a bet that by defusing the country's nuclear threat - even if just for a decade or so - he and his successors would have the time and space to restructure one of the United States' deepest adversarial relationships.
Mr Obama will be long out of office before any reasonable assessment can be made as to whether that roll of the dice paid off. The best guess today, even among the most passionate supporters of the President's Iran project, is that the judgment will be mixed.
Little in the deal eliminates Iran's ability to become a threshold nuclear power eventually - it just delays the day. To Mr Obama's many critics, including Mr Henry Kissinger, the architect of the China opening, that is a fatal flaw. It does nothing, he wrote recently with another former secretary of state, Mr George Shultz, to change "three and a half decades of militant hostility to the West".
Yet it is a start. Senior officials of two countries that barely spoke to each other for more than three decades have spent the past 20 months locked in hotel rooms, arguing about centrifuges but also learning how each perceives the other. Many who have jousted with Iran over the past decade see few better alternatives.
We have stopped the spread of nuclear weapons in this region.
US PRESIDENT BARACK OBAMA
SENSE OF RELIEF
We are certain that today the world has breathed a huge sigh of relief.
RUSSIAN PRESIDENT VLADIMIR PUTIN, in a statement published on the Kremlin's website
A NEIGHBOUR'S PERSPECTIVE
We have learnt as Iran's neighbours in the last 40 years that goodwill led us to harvest only sour grapes.
A SAUDI OFFICIAL, who asked to remain anonymous, speaking to Reuters
Iran will get hundreds of billions of dollars with which it will be able to fuel its terror machine.
ISRAELI PRIME MINISTER BENJAMIN NETANYAHU, about the easing sanctions
IT'S NO TO NUKE WEAPON
Iran 'will never seek a nuclear weapon, with or without the implementation' of the deal agreed with world powers in Vienna.
IRAN'S PRESIDENT HASSAN ROUHANI, speaking live on state television
We commend the hard work and efforts of all the parties involved. The next phase of the implementation of the agreement will be especially crucial. We urge all parties to fulfil their respective obligations and implement the agreement as soon as possible.
SPOKESMAN FOR SINGAPORE'S MINISTRY OF FOREIGN AFFAIRS
"The reality is that it is a painful agreement to make, but also necessary and wise," said Mr Nicholas Burns, who drafted the first sanctions against Iran, passed in the United Nations Security Council in 2006 and 2007 when he was undersecretary of state for policy.
"And we might think of it as just the end of the beginning of a long struggle to contain Iran. There will be other dramas ahead."
Teheran's nuclear programme is just one of its instruments of power to destabilise the Middle East. And there is the risk, especially in the next few years, that Iran's generals will compensate for the loss of their nuclear programme by stepping up their financing of Hizbollah and the government of President Bashar al-Assad in Syria, and by flexing their muscles in other conflicts across the region.
They have already built up a talented "cyber corps" of their own, and turned it on Saudi Arabia and, in more limited ways, the US.
Within a year or so, they will have a new influx of cash to finance those efforts.
Mr Obama is essentially betting that, once sanctions have been lifted, Iran's leaders will have no choice but to use much of the new money to better the lives of their long-suffering citizens. He has told his aides that he expects relatively little to be spent to finance terrorism or the emerging corps of Iranian cyber-warriors.
Ayatollah Khamenei and the Revolutionary Guard generals, dedicated to preserving the principles of the 1979 revolution, are taking the other side of that bet: That they can use the money and legitimacy of the accord to advance their interests, and to keep in check a young Iranian population that is clearly a lot less interested in next-generation centrifuges than it is in getting visas to visit and study in the West.
No one in the White House expects the Iranian government to be really interested in a far broader relationship any time soon.
"Four decades ago, it was clear that Mao had made a fundamental decision about his strategic shift, and he opened relations with the United States after concluding that the Soviet Union was a fundamental challenge to both of them," said Mr Karim Sadjadpour, who examines Iran policy at the Carnegie Endowment for International Peace.
"In Iran," he said, "there is hope for a strategic shift but it will take years to know".
NEW YORK TIMES